Elevated gene expression of interleukin-8 in cord blood is a sensitive marker for neonatal infection

Bacterial infection is a major cause of neonatal morbidity and mortality. E arly diagnosis is essential for a successful treatment and outcome. Cytokin e plasma levels are suggested to be sensitive parameters for the diagnosis of neonatal sepsis. The aim of this study was to assess cytokine mRNA expre ssion in cord blood cells as a marker for neonatal infection. In a prospect ive study, cord blood samples of neonates with septic bacterial infection w ere analyzed qualitatively and semiquantitatively by reverse transcriptase- polymerase chain reaction (RT-PCR) for mRNA expression of tumor necrosis fa ctor (TNF)-alpha, interleukin (IL)-1 beta, IL-6, IL-8, as well as for IL-8 cord plasma levels. Results were compared to those of non-septic neonates. A method was used requiring only a microvolume (25 mu l or less) of cord bl ood. Cord plasma levels of IL-8 were significantly elevated in septic infan ts (n = 9) when compared to infants with not confirmed sepsis (n = 22) and healthy infants that served as controls (n = 68) (median 1,686 vs 262.7 vs 33.1 pg/ml, P < 0.001). The presence of IL-6 and TNF-alpha gene expression was observed more frequently in septic than in non-septic patients; sensiti vity, however, reached only 56 and 67%, respectively. When using a semiquan titative approach for analyzing IL-8 mRNA levels, a high sensitivity (86%) and specificity (96%) for the detection of sepsis was achieved. A new metho d for the early diagnosis of neonatal infection is described measuring cyto kine mRNA in neonatal cord blood cells. With this molecular approach only a microvolume of blood is required for analysis.